Sound reproducer for talking machines



c. SCRABIC SOUND REPRODUCER FOR TALKING MACHINES Filed April 5, 1922 2Sheets-Sheet 1 i I I awue/ wtoz a1! flaraiik I c. SCRABIC SOUNDREPRODUCER FOR TALKING MACHINES z'sheezs-snee'. 2

: Filed April 5, 1922 box.

Patented Get. 28, 1924.

ED SITES CARL SGRABIG, or UQRBANA, OHIO.

SOUND nnrnonuonn roe TALKI G ACHINESJ Application fiiled' April 3,

To all whom it may concern:

Be it known that CARL ScRA ro, a citizen of the United States, residingat Urbana, in the county of Champaign and State of Ohio, has inventedcertain new and useful Improvements in Sound Reproducers for TalkingMachines, of which the following is a specification. Y i

This invention relates to an improved sound reproducer or sound box fortalking machines, and has for an object theprovision of a sound boxwherein the diaphragm will be mounted to vibrate within a closed chamberfor the purpose of confining within the sound box the sound disturbancescreated by the vibration of.thecdia-. phragm and preventing suchdisturbances from unduly escaping or becominguselessly dissipated intothe atmosphere without being amplified, and to providec a common sourceof sound amplitude. v An object of the invention resides in mounting thediaphragm so that similarior' exact conditions will prevail on bothsides thereof for the purpose of securing uniformity in the amplitude orpitohof the erence denote like and corresponding-parts throughout theseveral views thereof;

In said drawing: 5 i

Figure -1 is a vertical longitudinal sectional viewtaken through thesound box constructed in accordance with the present invention, I

- Figure 2 is a sectional view taken on the plane indicated by the line22of Figure 1, 4 i

Figure 3 is a sectional view on the line 3-3 of Figure-J1, and x VFigure 4 is a side elevation of the sound.

Referring more particularly to the -details of the invention the numeral1 designates the improved sound box comprising 1922. Serial No. 548,982.

upon the outer edge of which is placed and. secured a cover plate 5, thelatter being. se-- curedas at 6. to the flange 4, and when connected asshown this .casing will producean enclosed air tight chamber 7 inwhichadiaphragm 8 will be supported for vibration.

the present invention in its entirety; In the i The sound box is adaptedto be connected with the outer; end of a tone iarm 9"and my preferredstructure for effecting this connection: consists in providing-the outerThe said collar is provided-with radially extending knife edge studs ortrunnionsi 1 1, which are adapted to be received within.bayonetslots*12,1 provided ,in an exterior sleeve-'13, which is rigidlycarried by the casing. 2'. The sleeve 13' terminates forwardly in anannular vertical flange 15, and

an annular gasketlo is arrangedto be situated between the flange 15 andthe wall3. of the'casing to prevent direct contact of adjoining metallicparts. Screws 17 are employed to directlfybonnect the flange 15 with:the wall 3; The forward ends of the collar lOand sleeve 13 are providedwith registering-annular grooves, in which is seateda ring 18 of rubberor-other resilientmaterial,

which is confined between the wall 3 and the fiber Washer. .119 alsofseated within the grooves contained in the, ring 18. By thisconstruction it will be seen that-thefSound box may be detachablyandffiexibly connected-with the outer end of the tone arm by firstinserting the sleeve 13 over the collar 10 sothat the studs'll willbereceived 3 within the longitudinally"extending portions of thebayonetslots 12. Then, by'ro-- tating the sound box bodily aboutthe tone1 within the circularly disposed portions of.

arm -9, thesaid studs 11 will be positioned the slots 12, ,thus securelylocking the re- 7 producer in an operative position upon the tone arm;When the studs 11 are in'the circular portions of the slots 12thering'18 will becom'nressed, causing the same toexercise. a sufficient degreeof pressure toretain the studs in the'slightly enlarged. ends of theslots 12; and thereby preventing loss of adjustmenton the' part of thesound box.

Byformingthestuds 113111 triangular or knife'shaped form the samewillact as trunnions, permitting of limited oscillation on the part of thecasing 2 relative to the outer end of the tone arm. It will be observedthat the sleeve 13 is formed in two parts, the outer part servingtoconceal the studs 11 and the slots 12 so as 'topresent a neat andfinished appearance to the sound box when the latter is in use. Thisconstruction is fully set forth in my co-pending applica tion SerialNumber 4565M?) filed Mar. 28,

I The gist of the present invention resides inmounting the diaphragm 8within the casing 2 so that'the diaphragm will be completely encased bythe sound box and re 'moved from disturbing extraneous conditions, meansbeing provided for directing sound disturbances created on both sides oftheenclosed diaphragm to a common outlet, to insure unlformity 1n theamplitude of the sound disturbances set up on both sides ofconcentrically dispose-d within the enlarged bell shaped mouth 25 of thecollar 10, however, itwill be observed that the adjoining walls ofthe-mouth 25rand the conduits 23 v and 24; are relatively spaced. Tosupport the plate 20 within the casing, the wall 3 is provided with aplurality :of inwardly extend-ingscrews 2,6, which pass through open--in'gs provided peripherally in the circumferential portion 22! ofthe'plat e 20, and fiberor other similar washers 27 surround the screws26 and'are interposedbetween the wall 3 and the plate 20, so as to spacethe latter from the wall 3 to provide a space B whichcommunicate's withthe space B existingbe tween the conduits 23 and, 24, which'space' B isin direct communication with the end of the tone arm 9. Coopera "tivewith the plate 20 is a complimental plate 28, which is provided with anenlarged body portion 29 having an axial opening or conduit 30 formedtherein which is of the same size as the conduit 23 and issituated inregistration therewith. The. body portion 29 terminates near itsperiphery in a reduced wall 31 and is provided with acircumferentialflange 32, arranged to receive the circumferential portion 22 of; theplate 20,-the said flange 32 being provided with threaded openings 33'171 h ,ree'ept onof the ends of the screws 26, whereby when the latter aretightened into place the'same will serve to securely retain thediaphragm plates 20 and 28 in assembled relationship. By effectingrelative: approach between the plates 20 and 28 diaphragm gaskets 34 arecompressed and retained with the circumferentially reduced portions 22-and 31 of said diaphragm plates, for the purpose of engaging with theperimeter of the diaphragm 8,'freely supporting the latter for vibrationbetween said plates in a manner common to diaphragms of this charactergenerally.

The outer plate 28 is spaced from the cover or diaphragmclosure 5, andsimilarly the flange 32 is spaced from the casing flange 4 for thepurpose of producing spaces in engagement C and C" which communicatedirectly and freely with the spaces B and B. The closure 5 is formedwitha vertical de ression 35 providing. a groove 36, in whic is-positioned for movement the upper end of a stylus 37 having directconnection with the diaphragm 8. 'The lower endof the groove 36 isprovided with a compressible ring 38,

:which surrounds the stylus 37 with a suffidistantly from the diaphragmplates 20 and 28 so asto be capable of vibrating there'- b'etween" inconformity with the vibratory movement of the stylus. By forming theconduit 23 and the opening 30 of'the same diameter and inequally'spacing the diaphragm from the plates 20 and 28 sounddisturbances created by the vibratory movement of the diaphragm will beof equal pitch or amplitude onboth sides thereof for the purpose ofenabling thefsound disturbanc'es. to be properly equalized and to pass vin unison through the common outlet pro vided by the tone arm. I amaware'that structures have been heretofore proposed wherein a diaphragmis positioned for vibration within a closed chamber, and I therefore donot claim such a construction broadly, the present invention, however,

not only encases a diaphragm but produces a structure wherein thesources of amplitude on both sides of the diaphragm" are ofsubstantially the same proportions and wherein the sound waves aredischarged through a common outlet, namely, the tone arm, ofanassociated amplifier;

What is claimed is: r In a sound reproducer for talking ma.-

chines, an enclosed casing, a diaphragm sup portlng structure mountedWithin and spaced from the Walls of said casing, said structureincluding a compartment, a dia phragm mounted Within said compartmentand spaced equidistantly from the Walls thereof, an oscillating stylusextending into said casing for cooperation With said diaphragm, andconduits of equal diameter sides of said diaphragm, a third conduitcarried by the supporting structure and disposed in concentric spacedrelation With an adjacent conduit, all of saidconduits being incommunication With a commonsound 15 outlet.

In testimony whereof I aflix my signature.

CARL SGRABIC.

